U.S. investigators on the ground in Mexico are looking into the possibility that Tuesday’s ambush murder of ICE Special Agent Jaime Zapata was a “sanctioned hit” by the senior leadership of the Zetas drug cartel, Rep. Michael McCaul, R-Austin, told the Houston Chronicle late Thursday after receiving his latest update on the investigation.

Official photo

Rep. Michael McCaul

McCaul, chairman of the House Homeland Security Committee’s investigations subcommittee, said he had received “independent information that points to the possibility that this was a sanctioned operation at he very highest levels” of the powerful cartel.

“There appears to be some evidence that the attack was sanctioned,” McCaul added without providing details.

“ICE is trying to determine if these were Zetas operating in a rogue fashion or whether this was a hit sanctioned at the very highest levels of the cartel,” McCaul said.

“If it was sanctioned, it is very significant because this hasn’t happened before &#151 this would be a game changer. It means they are changing the rules and it opens up the possibility that they may try to conduct similar actions against other U.S. law enforcement agents in Mexico.”

McCaul said the episode raises questions about continuation of a 1990 policy in Mexico that bars U.S. personnel from carrying weapons.

It is not yet clear whether the two ICE agents targeted in Tuesday’s attack were armed.

“I don’t have a definitive answer. There were 83 shell casings at the scene. This was a total ambush on a massive scale with AK-47s. Even if (the agents) were armed, I’m not sure this could have been stopped.”

The attack already has stirred congressional calls for forceful action by the Obama administration &#151 actions that might cause strains in the deepening U.S.-Mexican collaboration in the war on drug traffickers shipping illicit narcotics north to the United States and U.S. arms dealers shipping combat-style weapons south to the cartels.

“We don’t know the motivation behind this,” McCaul said. “We only know that intentionally going after our agents is a significant departure from the way they have operated in the past.”

U.S. agencies are pouring back through intelligence gathered before the attack to try to determine whether the attack was ordered or sanctioned by Zetas’ leadership.

“They’re going back over everything to make that determination,” said McCaul.